Considerable work has been devoted to additives for controlling (preventing or reducing) deposit formation in the fuel induction systems of spark-ignition internal combustion and compression ignition (diesel) engines. In particular, additives to control fuel injector deposits, intake valve deposits and combustion chamber deposits is the focal point of a considerable amount of prior art. Despite these efforts, further improvements are needed and highly desired.
Many people have experienced difficulty in starting their fuel injected cars and trucks. This is especially true when the engine is hot. One possible cause is that lacquers build up in the fine orifices and the filter of the fuel injector, which restricts the flow of fuel; this is termed injector fouling. Another cause of injector fouling is when particulate contamination lodges in the injector nozzle (pintle) and prevents effective shut-off of the engine. This is known as pintle leakage. Many additives have been developed to add to the fuel to reduce these problems; however, significant improvements in injector design can also be of benefit.
Fuel injector performance is at the forefront of the DIG combustion systems as it relies heavily on fuel spray consistency to realize its advantages in fuel economy and power, and to minimize exhaust emissions. A consistent spray pattern enables more precise electronic control of the combustion event and the exhaust after-treatment system.
There are numerous references teaching gasoline compositions (fuel chemistries) for controlling injector fouling, for example, fuels containing Mannich detergents are disclosed in U.S. Pat. Nos. 4,231,759; 5,514,190; 5,634,951; 5,697,988; 5,725,612; and 5,876,468. However, none of these references teach the use of fuel compositions containing detergents for use in DIG or diesel engines with surface passivated injectors. These references also fail to suggest or disclose the surface texturing or passivation of the injector on the outside of the injector seat, in the vicinity of the nozzle which inhibits the formation of gum and/or coke, without adoption of special procedures and without installation of special equipment.
Little attention has, however, been given in the prior art to the role of the physical treatment of the engine components that come into contact with the fuel. For example, U.S. Pat. No. 3,157,990 discloses that certain phosphate additives are combined with the fuel which decompose in the combustion chamber and form a coating, probably a phosphate coating, on the internal engine surfaces. It is suggested that this coating effectively inhibits carbon deposit formation. Further, in U.S. Pat. No. 3,236,046 the interior surface of stainless steel gas generators is passivated with sulfurous materials to overcome deposition of coke on the surfaces of the gas generator. Passivation in this reference was defined as a surface treatment of an engine component which substantially reduces coke formation.
In view of the foregoing, it can be seen that it would be desirable to provide surface passivated and/or textured engine components (e.g., fuel containment articles and fuel injectors) so that deposit formation is avoided, eliminated or reduced. The disadvantages of the prior art processes and techniques include increased costs and promote uncertainty. It is a primary objective of this invention to overcome these disadvantages.